This invention relates to reducing electrical signal interference which arises in electrical connectors having closely spaced contacts. More particularly, the present invention relates to the reduction of cross talk induced by closely spaced contacts in electrical connectors.
High-speed data transmission cables are an integral part of computer networks and telecommunications systems. For example, a local area network (LAN) typically includes many individual computers and peripheral devices that communicate with one another through the high-speed data transmission cables. A LAN is typically implemented by physically connecting all of these devices with copper-conductor twisted wire pair LAN cables, the most common being an unshielded twisted wire pairs (xe2x80x9cUTPxe2x80x9d) of LAN cable having eight wires. The eight-wire cable is usually specifically configured as four twisted wire pairs. Each of the four twisted-wire pairs functions as a transmission line which conveys a data signal through the LAN cable.
A cable is usually terminated within a length which can range from a few feet to about 50 feet. The terminated cables are assembled with electrical connectors such as 110 connectors, D8GS connectors, RJ45 connectors and RJ11 connectors for further connection with communication equipment.
Cross talk is a measure of signal interference between twisted wire pairs of a LAN cable. Cross talk exists when signaling current in one of the twisted wire pair induces corresponding currents in the other twisted wire pair of the cable. Near end cross talk (xe2x80x9cNEXTxe2x80x9d) is a cross talk at the near end of a cable where the cable is terminated by an electrical connector such as a 110 connector, a D8GS connector, an RJ45 connector and an RJ11 connector. Maintaining a specified minimum level of NEXT at the electrical connector is important in order to maintain network work reliability.
Although electrical connectors such as 110 connectors, D8GS connectors, RJ45 connectors and RJ11 connectors have been used successfully, there is still room for improvement in the performance of the electrical connectors.
FIG. 1 shows a cable 100 having four twisted wire pairs. The cable 100 includes a jacket 111 and wires 120, 130, 140, 150, 160, 170, 180, 190 formed into twisted wire pairs. Insulating wire jackets 122, 132, 142, 152, 162, 172, 182, 192 of wires 120, 130, 140, 150, 160, 170, 180, 190, respectively, have different colors for identification. Each of pairs 120-130, 140-150, 160-170, 180-190 is twisted with different twist rates to reduce a signal interference between the pairs.
FIGS. 2A-2F show the components of conventional four piece type 110 connector 200 before assembly with the cable 100. The four piece type 110 connector 200 is designed to terminate a cable having four twisted pairs and to mate with a 110-type connecting block. The four piece type 110 connector 200 has a base member 202, a first housing member 204, a second housing member 206, a contact base 208 and a contact member 209 (for purposes of illustration and discussion, only the four top contacts are shown). The base member 202 receives the cable 100 and is fitted between the first housing member 204 and the second housing member 206. The base member 202 has channels 217a-217d constructed to receive wire pairs 120-130, 140-150, 160-170, 180-190 of the cable 100. For clarity in the drawings, only reference numerals for the first and last of comparable elements are shown. The channels 217a-217d of the base member 202 provide routing paths for the individual wire pairs 120-130, 140-150, 160-170, 180-190, 190, respectively. The base member 202 is also provided with insulation displacement contact (xe2x80x9cIDCxe2x80x9d) grooves 218a-218h to receive the IDCs of the contact member 209. The contact base 208 and contact member 209 are assembled, and then inserted into the base member 202 in which the cable 100 is mounted. The base member 202, first housing member 204, second housing member 206 and contact base 208 are usually made from a non-conducting injection-molded plastic, such as polycarbonate, ABS, or PVC, while the contacts 209 are made from a conducting material, such as stamped phosphor bronze that is plated with nickel and gold. The four piece type 110 connector 200 is designed to terminate the cable 100 and mate with a 110-type connecting block.
Upon assembly, the wires of the four twisted wire pairs are placed in channels 217a-217d of the base member 202 and the isolation of each wires is limited to a certain degree because of the material of the base member 202, i.e. plastic. Furthermore, the assembling procedure of the conventional four piece type 110 connector 200 is not an easy task.
We have created a modular type electrical connector which is configured to receive and terminate the wires of a cable and to be connected to a female part of connecting block. The modular type connector comprises multiple unit connectors which again may be divided into multiple sub-units. Multiple number of unit connectors are attached together for the multiple wires of a cable. The number of the unit connectors being used depends on the number of the wires of a cable. A portion of the surface of the unit connectors is shielded with a highly conductive material. As a result, upon being attached together, each of the signal conducting paths, i.e. the wires of a cable, IDCs, contact blades, are separated from each other by a highly conductive coating material on the surface of the unit connectors thereby reducing near end cross talk of the modular type connector while providing flexibility in configuration and assembly.
In one embodiment, two unit connectors are used to make a modular type electrical connector terminating one pair of twisted wires. Each of the unit connectors has a contact adapted to mount a wire of a cable, and a housing adapted to receive the contact. The inside or the outside of the surfaces of the housing is coated with a highly conductive material, thereby shielding the conducting path of the unit connector. Since the modular type connector is built with multiple number of unit connectors, different numbers of the unit connectors are readily attached together depending on the number of wires of a cable to be assembled.
In another embodiment, a modular type electrical connector comprises a receiver unit, a contact unit, a base and a cover. The modular type connector has a cable with four twisted wire pairs. Each of the receiver unit and contact unit comprises four receiver members and four contact members, respectively. Each of the receiver members and contact members is designed to receive a pair of wires of a cable and shielded with a highly conductive material thereby reducing the interference between each pairs of the four twisted wire pairs.
Further features, aspects and advantages of the invention are set forth in or are apparent from the following description and drawings.